The present invention relates to telecommunications and more particularly to backhauling telecommunications signaling protocol over packet-switching networks.
There is significant market need and technical interest in finding ways to communicate voice information and call signaling information over existing data networks. An example application in this field is sending telephone calls, including both the voices of the calling parties and call set-up, tear-down, and related signaling information, over a packet-switched data network. There is particular interest in providing telephone call capability using internet protocol (IP) technology, an example of which is providing the capability over the global, packet-switched public data network known as the Internet. A key motivation for this use of the technology is that voice calls carried over the Internet do not incur telephone call toll charges, which are imposed by long-distance carriers and certain local telephone call carriers in the public switched telephone network. In short, voice-over-Internet technology may offer callers the ability to place low-cost calls over open protocol networks.
A significant leap forward in this field has been taken by the introduction of protocol conversion and signaling switching systems. An example of such a system is the Cisco SC2200 Signaling Converter, commercially available from Cisco Systems, Inc. Other examples of such a system are described in U.S. patent application Ser. No. 08/904,295 entitled xe2x80x9cUniversal Protocol Conversion,xe2x80x9d filed on Jul. 31, 1997 by Lev Volftsun, et al., the entire contents of which are hereby incorporated by reference as if fully set forth herein.
Generally, such signaling switching systems are implemented by a highly specialized computer system that interfaces to the data network and the public switched telephone network. The computer system executes one or more signaling protocol software applications to carry out the function of the system. The signaling switching system may include one or more gateways that pass data signals to the telephone network and a media gateway controller that controls the gateways under control of a processor in the computer system.
One or more devices may be configured, by running appropriate application software, as call processing devices or as signaling gateway devices. In some configurations, a call processing device is located logically remote from a signaling gateway device, coupled to it by an Internet Protocol (IP) network. In this configuration, there is a need to send telephone call signaling information, formatted according to standard telephony protocols, from a signaling gateway device back across the IP network to a call processing device. This is referred to as xe2x80x9cbackhaulingxe2x80x9d the signaling information.
As voice-over-Internet systems become more popular, it is necessary to support a larger number of channels from the gateway. It is difficult, however, to scale call processing devices to handle an increasing number of channels from the gateways. For example, a call processing device may manage a separate IP connection for every signaling channel supported by each of the gateways.
Another difficulty in scalability is due to the capability of some gateways supporting multiple signaling protocols. One approach for handling such gateways is to provide an IP connection, not only for every channel on the gateway, but for every pair of channel and supported signaling protocols. For example, a gateway that supports 24 channels and 2 protocols would require 48 separate IP connections.
The performance in managing a separate IP connection for every channel, however, tends to degrade after a certain number of IP connections, because the number of file descriptors and other operating system resources are limited. For example, some UNIX(trademark) operating systems only allow up to 256 file descriptors, which translates to only about 250 supportable IP connections. When a call processing device is overloaded, a second call processing device would need to be purchased, often at a considerable cost.
There exists a need for a scalable telecommunications network that backhauls signaling data to a media gateway controller from gateways (signaling gateway or media gateway). There is also need for a backhauling methodology in a telecommunications network that is scalable also in terms of supporting multiple protocols and/or signaling channels multiplexed on a gateway.
These and other needs are addressed by the present invention, in which a generic backhaul protocol is employed for sending signaling data or messages between a gateway and a media gateway controller. The generic backhaul protocol provides a common message header that allows separate signaling channels and/or protocols to be specified. Consequently, the media gateway controller can use the information in the message header to multiplex signaling messages from a plurality of channels and protocols over a single IP connection, notwithstanding the number of channels and protocols supported by the gateway. Therefore, the media gateway controller is advantageously scalable in terms of the number of gateways supported instead of in terms of the much larger number of supported channels and protocols.
Accordingly, one aspect of the invention relates to a telecommunications network, comprising a gateway and a media gateway controller. The gateway, which is configured to convert between multiplexed voice data and voice data packets, is in communication with a packet-switching network and a node originating a voice call bearing voice data and signaling data according to a signaling protocol over a channel. The media gateway controller is in communication with the gateway, which is in communication with the packet-switching network and terminates the voice call. The media gateway controller is configured to control the gateway based on the signaling data to provide voice communications over the packet-switching network between multiple gateways. The gateway is also configured to extract the signaling data, to package the signaling data into a message, and to transmit the message to the media gateway controller. The message includes a message header indicating the signaling protocol and/or the channel and a message body containing a protocol data unit encapsulating the signaling data.
Another aspect of the invention pertains to a telecommunications device comprising a communication interface in communication with a gateway; one or more processors coupled to the communication interface; and a memory coupled to the one or more processors. The memory stores an arrangement of instructions, which, when executed by the one or more processors, cause the telecommunications device to perform the steps of: instantiating a plurality of protocol adapters and/or call instances for processing signaling data according to a plurality of signaling protocols and/or channels, respectively; receiving a message from the gateway, which includes a message header indicating the signaling protocol and/or the channel and a message body containing a protocol data unit encapsulating the signaling data; and identifying and causing a protocol adapter and/or call instance, instantiated to process signaling data according to the signaling protocol and/or the channel, respectively, to process the signaling data encapsulated in the protocol data unit based on the message header.
Yet another aspect of the invention involves a method of backhauling signaling data in a voice call from a gateway to a media gateway controller. In accordance with the method, the voice call is received, and the signaling data is extracted from the voice call. The signaling data is packaged into a message, which includes a message header indicating a signaling protocol and/or a channel and message body including a protocol data unit encapsulating the signaling data. The message is transmitted from the gateway to the media gateway controller.
Still other objects and advantages of the present invention will become readily apparent from the following detailed description, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the invention. Accordingly, the drawing and description are to be regarded as illustrative in nature, and not as restrictive.